Liquid separation apparatus



Oct. 12, 1965 KATSUJI HIRAHARA 3,211,535

LIQUID SEPARATION APPARATUS Filed June 18, 1962 INVENTOR KATSUJI HIRAHARA ATTORNEY United States Patent 3,211,535 LIQUID SEPARATION APPARATUS Katsuji Hirahara, San Jose, Calif., assignor to FMC Corporation, San Jose, Caiifl, a corporation of Delaware Filed June 18, 1962, Ser. No. 203,121 1 Claim. (Cl.23-280) This invention pertains to devices for separating liquids having different specific gravities, and more particularly relates to apparatus whereby a mixture of fat and aqueous extract under pressure may be separated into its components without the formation of large quantities of emulsions.

In the process of extracting usable fractions from such inedible material as bone, meat fats and similar slaughter house waste by subjecting such waste to steam under pressure in a pressure vessel, two immiscible liquid fractions result, namely, a fat or tallow fraction and aqueous protein fraction. It is highly desirable to separate these two liquid fractions and discharge them to atmosphere in separate streams since, if they are discharged to atmosphere while still combined, an emulsion will form which cannot be easily separated into the two component liquid fractions. Since the waste material in the pressure vessel is being continuously agitated, it is diflicult to separate the liquid fractions in this vessel. It is therefore an object of the present invention to provide means for effectively separating two liquid fractions from a liquid mass containing these fractions.

Another object is to provide apparatus for discharging two liquid fractions from a pressure vessel without causing the formation of large quantities of emulsion.

Another object is to provide an improved pressure vessel for separating a body of immiscible liquid into liquid fractions.

Another object is to provide means for purging, from various locations in a separator, undesirable impurities and minor accumulations of emulsion.

Another object is to provide improved means for controlling the discharge of the separated liquids from a pressurized separator.

Other and further features and objects of the presentinvention will become apparent from the following description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a diagrammatic elevation, with parts in section, of part of a fat recovery system in which the liquid separator of the present invention is incorporated.

FIGURE 2 is a longitudinal vertical section taken centrally through the separator of the present invention.

FIGURE 3 is an enlarged horizontal section taken along 3-3 of FIG. 2.

The embodiment of the separator of the present invention chosen for illustration in FIGURE 1 comprises a steel tank having a central cylindrical section 12 on which a lower, dished base 14 is welded and on which an upper, dished head 16 is bolted to form a rigid unitary structure that is supported on a plurality of rigid legs 18.

A manhole 20, which is formed in the head 16, is arranged to be closed by a removable cover plate 21. A short pipe 22 is welded in an opening in the head 16, said pipe having external threads at its upper end for connection to an external conduit. A relatively large pipe 24, which is welded in an opening 25 of the head 16, is provided with an annular flange 27 to which housing 30 of a liquid level control unit 32 is secured.

The base 14 has a central opening 38 in which a thick cylindrical closure plate 40 is welded. A pipe coupling 42 and a nipple 44 are welded in openings in the closure plate 40. The nipple 44 is connected in a drain line 46 B,Zll,535 Patented Oct. 12, 1965 which has a manually operable valve 48 therein, and the coupling 42 is connected in a drain line 50 which has a flow control valve 52 therein.

The central cylindrical section 12 of the tank 10 is provided with a pipe coupling 60 which extends through the side wall of the vessel and is connected to a conduit 62 leading from the discharge outlet 64 (FIG. 1) of a pressure vessel 65 in which the slaughter house waste products are being processed. A second pipe coupling 66, which is secured in and extends through the tank wall, is connected in a purge line 67 which also includes a manually operable valve 68. Another pipe coupling 69 is fixed in an opening in the wall of the tank 10. Internally of the tank, the coupling 69 is connected in flow communication with an overflow weir 72 by means of a line 73 which includes a union L 74. The weir 72 is an annular member of semicircular cross-section which is supported by fixed brackets 75 (one only being shown) which project inwardly from the side wall of the tank. The coupling 69 is also connected to a line 78 that leads to an automatic vent trap 79 (FIG. 1) which has a discharge pipe 80. It will be evident that, when the lines 73 and 78 are connected to coupling 69, the weir 72 is supported at a predetermined elevation in the tank. Other couplings 69a and 69b, shown in phantom lines, may be secured in the tank wall so that the weir can be selectively positioned at different elevations. It will be evident that additional support brackets 75 will be provided to support the weir at the selected level.

A conduit 82 (FIG. 1) establishes communication between the interior of the head 16 and the interior of the vent trap 79. A second conduit 84 is connected to the pipe 22 atop the head 16 and establishes communication between the interior of the head 16 and the interior of the pressure vessel 65 and, accordingly, the conditions of pressure and temperature in the head are identical to those in the vessel 65.

A standpipe 88 is removably mounted internally of the tank 10, said standpipe having a frusto-conical perforated screen 89 welded on its lower end and provided with three bars 90 (FIG. 3) welded to its inner surface. As seen in FIG. 2, each bar 90 is inclined upwardly and is adapted to coact with one of three hooks 91, which are fixed to and project upwardly from the base plate 40, to lock the standpipe in position in the tank. With this arrangement, the screen 89 can be quickly and easily removed from the tank for cleaning merely by removing the manhole cover 21, grasping the upper end of the standpipe, rotating it clockwise (FIG. 3) until the inclined bars 90 are out from under the hooks 91, and then lifting the standpipe 88 and screen 89' up through the manhole 20.

A drain pipe is disposed inside the lower end of the standpipe 88, being threaded into the coupling 42 which leads to discharge line 50.

As previously mentioned, the liquid material which flows by gravity from the pressure vessel 65 through line 62 and into the tank 10 has two immiscible portions, namely, a fat or tallow fraction and an aqueous protein fraction. Since the fat or tallow is a lighter fluid than the protein extract, the tallow rises to the upper portion of tank 10 while the protein extract sinks to the lower part of the tank. The level of the total liquid in the tank is kept constant due to the fact that the tallow overflows into the weir 72 and is discharged by means of the automatic vent trap 79. This trap may be in the form of a float valve drain unit such as that marketed by Fisher Governor Company of Marshalltown, Iowa, as type 37 Continuous Drainer. The tallow that is discharged from trap 79 may be collected in any suitable container or storage tank.

When the liquid separates into its two components due to the difference in the densities of the components, an interface line or layer L (FIG. 2) is formed at the boundary between the upper tallow and the lower protein extract. The level control unit 32 is a commercial unit adapted to control the opening of the valve 52 in response to variations in the position of the interface layer L. The control unit 32 may be of the type marketed by the above-mentioned Fisher Governor Company as type 249P, series 2500, Level Trol. In general, this unit comprises a float 96 disposed in a guide housing 97 which is fixed inside the tank by brackets 98. A rod 99 extends upwardly from the float 96 and, by means of other links and levers (not shown), is arranged to open or close a valve (not shown) in unit 32 in response to variations in the height of the interface L. The valve inside the unit 32 is arranged to direct an operating fluid, such as air, to the diaphragm valve 52 to control the opening or closing of the valve therein. The arrangement is such that, if the level L rises, the valve 52 is opened to permit faster removal of the aqueous protein extract through line 50. Similarly, if the interface level tends to lower, the valve 32 is moved toward closed position to decrease the discharge rate.

During the operation of the system illustrated 'in FIGURE 1, raw material is fed to the pressure vessel 65 through a pressure valve 100. The valve 100 may be of the type disclosed in the United States patent to William de Back, 2,638,137, and the pressure vessel 65 may be of the type disclosed in the United States patent application of Frank D. Hickey, Serial Number 17,918, which is assigned to the assignee of the present application. In the vessel 65 the material is subjected to steam at a pressure in the range of from 50 to 120 p.s.i.g. through a line 102 from a source 103 with suitable pressure and temperature control devices (not shown) being provided as disclosed in the pending patent application of Frank D. Hickey mentioned hereinbefore. In the vessel 65 there is a screw 101 extending along the length of the vessel which continuously agitates the material being processed. As the material is processed, it is separated into a portion consisting of solid material, and a liquid portion containing a fat fraction and an aqueous protein fraction. The screw advances the solid material upwardly along the vessel 65 toward the upper end where it is discharged through a suitable pressure valve. The liquid portion accumulates at the lower end of the vessel 65, drains out of the vessel through opening 64, and travels through conduit 62 into the tank 10 through coupling 60.

The tank 10 is of adequate size to allow suflicient separation of fat from the aqueous protein due to the difference in the densities of these products. In one satisfactory installation, the tank was approximately 3 feet in diameter and approximately 4 feet from top to bottom.

As the fat fraction and the protein fraction separate out, the interface layer L is formed, and this layer is maintained at a substantially constant elevation by the interface control unit 32 which operates the discharge valve 52 to regulate the rate of discharge of the protein fraction through discharge line 50 It should be particularly noted that, in order for the protein extract to reach the discharge line 50, it must pass through the screen 89 and then move upwardly inside the standpipe 88 to an elevation about the upper open end of pipe 95. Fines and solid particles are, of course, removed by the screen 89. In addition, the upward travel of the protein extract in the standpipe lengthens the time that the liquid is in the tank and, therefore, the standpipe discharge arrangement assures that there will be a maximum time for separation of the fat from the protein extract. Some fines and impurities will settle to the bottom of the standpipe and they may be quickly removed by periodically opening the manual valve 48. Due to the fact that the line 84 interconnects the vessel 65 to the interior of the tank 10, the contents of the tank are also under a pressure in the range of 50 to 120 p.s.i.g.

Accordingly, when valve 48 is opened, any impurities or fines collected adjacent the plate 40 will be forced out through line 46.

Similarly, when manual valve 68 is opened, any fines or emulsions collected at the interface layer L will be forced out of the tank through line 67.

It will also be apparent that, since the pressure inside the tank is equalized with the pressure inside the vessel 65, the interface layer L is not adversely affected by unbalanced pressure conditions.

The fat or tallow fraction overflows into the weir 65 and is discharged through the float valve control unit 79. If the conduits 73 and 78 are large enough so that the fat does not occupy the entire cross-section of the conduits, the conduits themselves will act as an equalizing line, establishing communication between the inside of the tank 10 and the inside of the control unit 79. With such relatively large conduits, the equalizing line 82 need not be provided.

From the foregoing description, it will be recognized that the present invention provides a simple, effective mechanism for separating two liquids, having different densities, and discharging them in separate streams. The adjustable weir 72 makes possible the adaptation of the unit for use with pressure vessels 65 of various capacities since, in general, the height to which the liquid will rise in the tank depends upon the output of the pressure vessel. It will also be noted that the equalizing line 84 makes possible the separation of the liquid fractions under pressure in the tank, and prevents steam vapor or the like in the system from agitating the interface level. Further, the simple, quick-disconnect connection between the standpipe 88 and the bottom of the tank greatly facilitates the cleaning of the screen 89. It will also be evident that the location of purge lines 46 and 67 makes possible the removal of fines and impurities at the areas where they tend to accumulate.

While a particular embodiment of the present invention has been shown and described, it will be understood that the separator device of the present invention is capable of modification and variation without departing from the principles of the invention, and that the scope of the invention should be limited only by the scope and proper interpretation of the claim appended hereto.

Having thus described my invention, what I claim as new and desire to protect by Letters Patent is:

Apparatus for separating liquids of different densities from a liquid mixture that has been formed during the processing of meat scraps and the like comprising, in combination, a pressure vessel, first means for introducing steam under pressure into said vessel, second means for introducing material to be separated into said vessel, mechanical conveyor means in said vessel for moving said material, a settling tank, a supply conduit arranged to convey the liquid mixture from the pressure vessel to said settling tank, said tank having an upper section adapted to receive the lighter liquid fraction as said mixture separates into its components due to the difference in densities of the components and a lower section adapted to receive the heavier liquid fraction, a discharge conduit communicating with each section of said tank, and a separate conduit establishing communication between the interior of the pressure vessel and the interior of said tank to subject the interior of said tank to a steam atmosphere that is substantially identical to that in the pressure vessel whereby separation of the mixture takes place in said tank under the same pressure conditions as those in the pressure vessel.

References Cited by the Examiner V UNITED STATES PATENTS 7l9,028 l/03 McDougall 137-l92X 1,113,207 10/14 Durant 137-192 (Other references on following page) 5 6 UNITED STATES PATENTS 2,967,618 1/ 61 Vane 21084X 7 15- Ashb 210 537 2,98 ,360 5/61 Smith .-l 210114X g, 210479 X 2,996,188 8/61 May 210-114 5/38 Parsons 210114 11/39 Millard 210 537 X FOREIGN PATENTS 12/40 Heathman et a1. 137-192 X 812,554 9/51 Germany.

2/ 49 Kracklauer 210--479 727,186 3/55 Great Britain. 2/57 C01k6t .210540X 9/57 Griswold 210 115 X REUBEN FRIEDMAN, Przmary Exammer. 3/59 Lawson 210---221 X 10 HERBERT L. MARTIN, Examiner. 

